https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99441
Bug ID: 99441
Summary: [GCOV] Wrong coverage with complex "if" condition
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: gcov-profile
Assignee: unassigned at gcc dot gnu.org
Reporter: njuwy at smail dot nju.edu.cn
CC: marxin at gcc dot gnu.org
Target Milestone: ---
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure -enable-checking=release -enable-languages=c,c++
-disable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.2.0 (GCC)
$ cat test.c
typedef __SIZE_TYPE__ size_t;
typedef __UINTPTR_TYPE__ uintptr_t;
struct S {
int a;
unsigned short b;
int c, d, e;
long f, g, h;
int i, j;
};
static struct S *k;
static size_t l = 1;
int m;
static int bar(void) {
unsigned i;
int j;
if (k[0].c == 0) {
++m;
size_t n = l * 2;
struct S *o;
k = (struct S *)__builtin_realloc(k, sizeof(struct S) * n);
for (i = l; i < n; i++) {
void *p = (void *)&k[i];
int q = 0;
size_t r = sizeof(struct S);
if ((((uintptr_t)p) % __alignof__(long)) == 0 && r % sizeof(long) == 0) {
long __attribute__((may_alias)) *s = (long *)p;
long *t = (long *)((char *)s + r);
while (s < t)
*s++ = 0;
} else
__builtin_memset(p, q, r);
}
}
return 1;
}
int main() {
k = (struct S *)__builtin_malloc(sizeof(struct S));
__builtin_memset(k, '\0', sizeof(struct S));
k->a = -1;
for (int i = 0; i < 15; ++i)
bar();
}
$ gcc -O0 --coverage test.c;./a.out;gcov test;cat test.c.gcov
libgcov profiling error:/home/wangyang/coverage/found
bug/gcc/test.gcda:overwriting an existing profile data with a different
timestamp
File 'test.c'
Lines executed:95.45% of 22
Creating 'test.c.gcov'
-: 0:Source:test.c
-: 0:Graph:test.gcno
-: 0:Data:test.gcda
-: 0:Runs:1
-: 1:typedef __SIZE_TYPE__ size_t;
-: 2:typedef __UINTPTR_TYPE__ uintptr_t;
-: 3:
-: 4:struct S {
-: 5: int a;
-: 6: unsigned short b;
-: 7: int c, d, e;
-: 8: long f, g, h;
-: 9: int i, j;
-: 10:};
-: 11:static struct S *k;
-: 12:static size_t l = 1;
-: 13:int m;
-: 14:
15: 15:static int bar(void) {
-: 16: unsigned i;
-: 17: int j;
15: 18: if (k[0].c == 0) {
15: 19: ++m;
15: 20: size_t n = l * 2;
-: 21: struct S *o;
15: 22: k = (struct S *)__builtin_realloc(k, sizeof(struct S) * n);
30: 23: for (i = l; i < n; i++) {
15: 24: void *p = (void *)&k[i];
15: 25: int q = 0;
15: 26: size_t r = sizeof(struct S);
30: 27: if ((((uintptr_t)p) % __alignof__(long)) == 0 && r %
sizeof(long) == 0) {
15: 28: long __attribute__((may_alias)) *s = (long *)p;
15: 29: long *t = (long *)((char *)s + r);
120: 30: while (s < t)
105: 31: *s++ = 0;
-: 32: } else
#####: 33: __builtin_memset(p, q, r);
-: 34: }
-: 35: }
15: 36: return 1;
-: 37:}
-: 38:
1: 39:int main() {
1: 40: k = (struct S *)__builtin_malloc(sizeof(struct S));
1: 41: __builtin_memset(k, '\0', sizeof(struct S));
1: 42: k->a = -1;
16: 43: for (int i = 0; i < 15; ++i)
15: 44: bar();
-: 45:}
Line #27 should only be executed 15 times
